Ashes of the Empire
Ashes of the Empire is one of the maps included with the base game, and is the setting of a campaign by the same name, which depicts the collapse of the Steel Empire, and the spower struggle between the various breakaway factions which rose from its... ashes.
Specifically, the campaign sees the player attempt to survive and thrive in the midst of the ongoing civil war.
Geography
Measuring 45x45km, this is a primarily land-based map, and thus heavily favours the use of defensive Structures and ground-based Vehicles (although aircraft are also viable).
Doctrine
By default, there's a construct size limit of 2'500m3 in place, to encourace the player to learn how to build space-efficient subsystems for their constructs.
The player's is also encouraged to develop their fleet management skills, as it's generally not possible to develop a practical do-everything construct within the size limit.